Dental casting flask



June 12, 1923.

N. O. LYNN DENTAL;- CASTING FLASK Filed Nov. 19.' 1921 .iaten'ted Junel2,

NATHAN-dunner TUCSOMARIZONA.

. DENTALCASTING FLASK.

Application aieaivvmier 1e, 1921.l seiiaiio.` 516,442.r

17.70v 4 czZvZ .iolioinf it may `vince/.Yat

.Be it known that 1NA-THAN O. LYNN,

ay citizen of the lUnited States, residing at' gold, aluminum,- andother VKmetallic [alloys iscaccomplishedlbhy the preparing of molds foreach .individual case, wherein an investment, vsuch as ,af body offmoldforming-finaterial, is placed in the flask in plastic state, andxapattern having the form of ythe'articleto be produced is embeddedlwithin the same, the pattern beingnifade ofa volatile substance, suchaswax or'thelil {`e, which will be .destroyedby ,the alctionof heatapplied to the flask .for thev purpose and for the driving from theinvestment of `allof its moisture content. Whenproperly heated, theinvestment'will hardeinfand the waa pattern be destroyed, whereb-ya moldspace or cavity will ,bel `providedor v,the reception therein: of thedesired`v molten metal from whichV thearticle is tovbe produced, andthis `molten metal has `tobe forced into the mold i space or cavity,vand is accomplished either' bythe useof a pressure or vacuum' machine.When hardened, the investment is oifa rela# tively great porosity, and,in the use of a pressure machine, the molten metal is forced downwardlyof the sprue holeleading into 'the moldspace or ca'v'ity,uiiider theaction ofthe pressureof` such machine, while in the use of the .vacuummachine, the action of the.

same drawsA out all of the airfro'in the pores of thefinvestn'ient withthe,` result that the molten metalf isv forced 7intothe mold spaceforcavity under atmospheric pressure. Heretofore,; inthe practicef'and inthe use of known types of 'dental flasks crniolds, it very often, occursthat, byv freason 'of inaccuracies the positioning oithefwaxeipatf ternwithin theinvestment, themoldfspace orl cavity v'is formed too nearltheend ,on the latter so ythat the outer wall thereoffi'sf't@ Weak towithstand vthe pressure or .vacuum Vmethods of introducing the inoltenlmetal "toy the mold' space" or cavity,` and is; .broken fdown, wherebythe lentire operationA vis a failure, with a consequent serious lossintiin,elabor, andinalterial'in such operationy. as well as in thepreparation of a new mold andthe carryingout of the ,additional castingoperation.

Thev principal Vlaslroii the class mentionedfandone' wheres of anyparticularpiece ofdentalfvvorkfis assured. 4 t Y Another' objectof theinvention; is'to.prof` vide yfor a .casting flask of the typef-menQ`object of` theI present'infveiition, therefore, is to lprovide forafcafsting lin the. foregoing/defects and. disadvantages inthe structureand operation of such .des ,l

tioned, and one-of anvextreinely simple and inexpensive constructionandV arrangement of parts, and wherein the wax `pattern'may bevaccurately einbecldedwithin `th'e`-, i'nvesti thepressure'or vacuummethods offorcing v .the molten metal into thef cavity.

v Az further object of the finventioniis to provide fora castingiiaslgofthe characterset i mold l space :jor

forth, and one' wherein, provision ifs made cross sectional area. of"the porous investl` ment, such as loften( results in the" breakinz downof the weaker wall'portion o f'thfela't-y i' tens, or` in thejfailurejto forceV the molten..

inetal'into 4the mold through lossfofthis pressure or suction,a'meansbeing provided whereby such pressurey is exerted centrallyV ofthebody of the linvestment li'roinoiie end to the other thereof, andfinline with"` the i mold 'space or cavity therein,"` for."suchfipuifpose,` as w'ellv as to assure ,of the. inoltenineta'l -illingthemold space or 4cavity,'and-fnot y i otherwise being spread to anappreciable extent into the pores of the investment.

Another' object of the invention is to provide for a casting flask ascharacterized, and one wherein the end wall of the investment or moldbody, in proximity to which the mold space or cavity is formed, issuitably reinforced in a manner to prevent the breaking down thereofunder the effects of pressures used for the forcing of the molten metalinto such space or cavity.

lVith the foregoing and other objects in view, the invention resides inthe certain novel and useful construction, arrangement and operation ofparts, as will be hereinafter more fullv described, set forth in theappended claims, and illustrated in the accompanying drawings, in whichl Figure 1 is a vertical section through a preferred embodiment of thecasting flask,

and showing the parts thereof in the initial.

or mold preparing position of operation.

Fig.v2 is a view similar to that of Fig. 1, but showing the castingflask in reversed position and ready for the casting operation,

Fig. 3 is a horizontal section taken on the line 3-3 of Fig. 1, y

Fig. 4 is a horizontal section taken on the line 4-4 of Fig. 1, and,

Fig. 5 is a top plan view of the flask as shown in Fg- 2- Referring tothe drawing, wherein similar characters of reference designatecorresponding parts throughout the several views thereof, the preferredembodiment of the .invention as shown therein comprises a cylindricalflask body or casing formed to provide an upper portion 10, and avlowerportion 1,1, said portions having their connected ends interiorly andexteriorly threaded, as at 12, for adjustable engagement one withrespect to the other, the lower portion 11 beingof a greater length thanthe upper portion 10, substantially as shown.

The lower portion 11 is preferably formed to provide an inturned flangeportion 13 at its lower end, and has its walls slotted as at 14, for aportion of its circumference, at a point immediately inward of theflange portion 13, for the insertion therethrough V of a perforatedremovable bottom member or plate 15, the inner portion of the latterbeing of a width corresponding to the mean diameter of the opening`through the flange portion 13, and of a. length, to have its inner endsupported on the inner wall thereof, while the outer end portion* 16 iscoextensive with the slot 14 and has its outer edge curved on a lineconforming with the curvature of the outer surface of the cylindricalbody portion 11` except for a. centrally and outwardly extended lingergripping portion 17, by means of which the insertion and withdrawal ofthe plate 15 is readily facilitated. The upper portion 10 of thecylindrical body is provided with a concaved wall 18, spaced inwardly ofits upper end, and which has a sprue hole 19 at its cent-er for purposeswhich will be hereinafter more fully explained. r

`In the preparing of the mold, with its upper and lower portions 10and11 of the ask unthreaded, and with the bottom plate 15 removed fromthe lower portion 11, the

-upper portion 10 is placed top side down on the topy of a work-bench orother suitable support (not shown), and is centered over a sprue former20, which is circular in form and has aconvex upper face provided withan opening at its center and preferably filled with a suitable plasticmaterial orwax filling 21 for the engagement therein of a sprue formerwire 22, which is now passed downwardly through the central opening 19formed in the concave wall 18, and has its lower end forced into the waxfilling 22 within the opening of the support 2() for the purpose ofsupporting in proper position, within the flask body, of a pattern 23fixed onits upper end. The lower portion 11 of the flask is now screwedonto the upper portion 10, as it stands, and

until the wax pattern 23 is at the desired distance below the open orbottom end of the flask. This pattern 23 is in the exact form of thedesired dental article or restoration to be cast, and ispreferablyformed of a wax capable of being readily v'oliVitli the parts inthevposition as thus` de-` scribed, the flask body is'now filled with asuitable mold forming material or investment 24 in plastic state, whichis passed through the central opening 19 and fills the space between theconcaved'wall 18 and the convexed face of the sprue former 20, as

well as the body ,ofv the flask proper, when the bottom plate 15 will beinserted inwardly of the slot 14 and in a manner to have its inner endportionseat against the inner wall of the flange 13, in which condition,it is left standingr until the investment material 24 has hardened. Thesprue former 2O is then disengaged yfrom the flask end and the spruewire 22, by aquarter turn, when heat is to b .e applied to the flask forthe purpose of evapora-ting all moisture from theyinvestmentfmate'rialandv for the destruction, melting orV vaporizing of the wax pattern 23.By thusV destroying the wax pattern 23, a vmold space or cavity 23", asshown in Fig. 2, will be provided within the hardened body of,therplastic material or'investment 24, and, upon the lwithdrawal of thesprue former or wire 22, a sprue duct will extend from the moldrspace orcavity 23 to and open through theupper end wall of the mold body orinvestment 24, and centrallyv with respect to the sprue hole 19 with theconcaved wall 18 of the upper portion 10 of the flask. For the forcingof the molten metal into the mold space or cavity 23, the flask isturned end for end from its original position, and the molten metal isforced downward of the sprue duct or passage 22 and into the mold spaceor cavity 23', the air pressure used for such purpose passing downwardlyofthe sprue hole 19 through the pores of the mold body or investment 24,and out of the perforations formed in the bottom vplate 15 at'the lowerend. of the lower portion 11 of the flask. After the mold space orcavity 23 has been filled with the molten metal, the flask is allowed tocool, when the yupper part 10 thereof will be removed from thelowerportion 11, preferably'by softening the in- `Ivestment 24 by soaking inwater and unscrewing the parts of the flask, .when the investment 24maybe easily cleaned away from the inside of the flask and the castingremoved therefrom. l

The positioning of the pattern 23 at a proper and necessarilypredetermined dis-l tance inwardly of the lower end of the in- -vestment24, so that a suflicient thickness of the latter will be provided atthis side of the mold space or cavity 23.,'is readily accomplished bythe lengthening or shortening of the flask body, it being very essentialin this particular casting art, that the wax pattern 23 be placed, atthe time of its being embedded in the plastic investment, at a definitedistance from the lower end or bottom of the flask so that, when themolten metal is forced down through the sprue hole 19, and the sprueduc-t 22 and into the mold space or cavity 23', it will remain withinthe latter, since the pressure used for the forcing actionwill have beenreduced by reason of the escape of the air through the pores of the moldbody or investment 24, whereas, should the mold space or cavity 23 beplaced too far from the lower end or bottom of the investment 24, theeffects of the pressure would be such as to force a goodly portion ofthe molten metal into the pores of the mold body or investment, sincethe lessened distance between the mold space or cavity 23 and the spruehole I19 would not be suflicient to permit of the necessary rapidseepage of air through the pores of the investment for the reducing ofsuch pressure. However, if the mold space or cavity 23 is formed tooclose to the lower end or bottom wall of the mold body 24, the lowerwall portion of the latter will be broken by the pressurewithresult thatthe metal will lrun out at the "bottom ofthe flask, :causing fail..

ure to the operation as Vhas beenhereinbefore eXPlained.y v

From,y the foregoing,lit=will be readily -ap parent .that'while a.preferredkembodiment of the castin '.mold...orfl`ask has 'beend'e- .i y

Having thus fully described the invention,

what is claimed, is

1. In a casting flask as characterized, al

flask body open at one end and having 'a sprue hole opening cent-rallyofthefclosed end thereof, said flask body beingformedl to provide upperand lower separable secf tions one in threaded engagement with theother,a sprue former adapted vfor insertion into said flask through thevspruehole in the closed endthereof, a, pattern carried at the insertedend of said sprue former and adapte` l ed to be embedded in aplasticmaterial filling said flask body, and a removable perf' forated platecarried at the open end of said flask body for reinforcingthe plasticfilling during the casting operation, the separable sections ofl saidlflask body being relatively. adjustable for effecting the properposition!v p I pattern within the plastic filling f v k 2. In a castingflask for the purpose set ing of said therein.

forth, comprising a flaskY body formed to. *Y

provide separable upper and lower sections,

.said upper section' having formedintegral.

with vits inner vface,V at a 4point removed from the upper end thereof aconcave wall formed with a centrally disposed opening,`

a removable perforated bottom plate engaging in the lowersection inproximity toits lower end,'a sprue former vadapted for insertioninwardly with respect tosaid wall and` through said opening and adaptedto carry a pattern at the inserted end thereof,

and means for adjusting the sections of said flask body for affectingthey-proper positioning of the pattern on the sprue former.

3. In a. casting flask for the purpose set forth, a flask body formed ofa pair of Sections adjustably connected together, one ofv said-'sectionshavingv formed integral with its inner face a concave wall lformed witha centrally disposed opening, and the other of said sections providedwith a removable perforated bottom plate.

4. In a casting flask for thepurpose set forth, aask body formed of anupper and a lower separablesection, said upper section j having formedintegral with its innerigface at a. point removed from the upperterminus thereof a concave wall formed with av center just-ablyconnecting them together for effecting the proper positioning o'l thepattern therein. f

In testxnonT whereof, I my Signature hereto.

NATHAN o. LYNN.

